For years, campaigners have urged the RSPCA to take a stand against the Kennel Club and Crufts, the dog show it promotes. Now a BBC documentary is showing the horrible genetic diseases caused by years of canine inbreeding, the charity has decided to scrap its usual stall at Crufts.

Pedigree Dogs Exposed takes the cavalier King Charles spaniel as one example. Many are suffering from syringomyelia, which is when a dog's brain is too big for its skull. It is compared to a size 10 foot being shoved into a size 6 shoe.

During the course of its investigations, the BBC found boxers suffering from epilepsy, pugs with breathing problems and bulldogs who are unable to mate or give birth unassisted. It compared the breeding to Nazism because of its obsession with breed purity.

The RSPCA's chief vet, Mark Evans, said in the programme: "What I see in front of me is a parade of mutants. It's some freakish, garish beauty pageant that has nothing frankly to do with health and welfare."

The charity later published a clarification of Evans' comments on its website: "The 'parade of mutants' comment is Mark's personal view. The RSPCA is, however, concerned about the unacceptably high levels of disability, deformity and disease affecting pedigree dogs - and this includes animals entered into 'best of breed' classes in dog shows like Crufts."

Last month, the BBC said it was contemplating withdrawing from live coverage of the event, which it has been showing for more than 40 years.

The RSPCA says it wants to see a change in the rules at dog shows to prioritise health, welfare and temperament over appearance. It also wants to see the development of health-focused breeding strategies for individual breeds, including steps to increase their genetic diversity.

But why has it taken so long for an organisation which is supposed to promote animal welfare to stand up to the Kennel Club and withdraw its Crufts stand? And should the organisers be allowed to continue their "parade of mutants"?